1. Field of the Invention
The present invention relates to a system for charging a battery of a legged mobile robot.
2. Description of the Related Art
For example, Japanese Patent Laid-Open No. 2001-179663 discloses a system for charging a battery of a legged mobile robot configured as described below. A power receiving connector used for charging an internal battery is provided near the hip part of the robot, and a power receiving terminal is exposed on the surface of the power receiving connector. On the other hand, a charging station for charging the robot has a power supplying connector, and a power supplying terminals is exposed on the surface of the power supplying connector. The robot moves closer to the charging station and connects the power receiving connector to the power supplying connector. As a result, the power receiving terminal and the power supplying terminal are connected to each other, and the robot is charged.
In the system disclosed in Japanese Patent Laid-Open No. 2001-179663, in order to facilitate alignment between the robot and the charging station, the power receiving connector has a trapezoidal profile narrower at the end close to the power supplying connector, and the power supplying connector has a recess shaped to confirm to the profile of the power receiving connector. Therefore, even if the robot to be charged is slightly misaligned, the trapezoidal power receiving connector is guided by the recess in the power supplying connector and connected to the power supplying connector, and thus, the positioning of the robot to be charged is facilitated (see the paragraphs 0139 and 0145 and FIGS. 7 to 9).
When alignment of the system configured as described above is performed, since the charging station is fixed to the floor or the like, the connector on the robot has to be moved to achieve alignment between the connectors. In the case of the legged mobile robot disclosed in Japanese Patent Laid-Open No. 2001-179663, since the power receiving connector is attached to the hip part, the joints of knees, ankles or the like have to be moved, or the legs have to be displaced, in order to move the power receiving connector.
However, in the case of the legged mobile robot, if the hip part is moved horizontally by moving the joints of knees, ankles or the like without displacing the legs, the center of gravity of the robot is displaced, and therefore, the robot has to be charged with the joints being subjected to a moment. If the robot is charged with the joints being subjected to a moment as described above, additional power is required to maintain the posture of the robot, and there is a possibility that the power consumption during charging increases. If the power receiving connector is displaced by displacing the legs, the legs of the robot are displaced with the power receiving connector and the power supplying connector being partially in contact with each other, so that the connectors are overloaded, and the connectors can be damaged.
Furthermore, the power receiving terminal disclosed in Japanese Patent Laid-Open No. 2001-179663 is always exposed to the outside, and therefore, if the surface of the terminal is soiled with something, the electrical contact between the power receiving terminal and the power supplying terminal can be poor. Furthermore, in the case of the arrangement disclosed in Japanese Patent Laid-Open No. 2001-179663, if spark discharge (ark discharge) occurs when the power receiving terminal and the power supplying terminal are connected to each other for charging of the robot or disconnected from each other after charging of the robot, the spark discharge can cause deterioration of the terminals, the deterioration of the terminals can cause an increase of the resistance between the terminals, and the increase of the resistance can cause heat generation.